The present disclosure is generally related to mutant and genetically modified filamentous fungal cells and methods thereof for use in the production of proteins of interest. More particularly, as described herein, the mutant and/or modified fungal cells (strains) of the disclosure are well-suited for use in industrial scale fermentation processes for the enhanced expression/production of proteins of interest in the absence and/or in the presence of an inducing substrate.

The present disclosure is generally related to mutant and genetically modified filamentous fungal cells and methods thereof for use in the production of proteins of interest. More particularly, as described herein, the mutant and/or modified fungal cells (strains) of the disclosure are well-suited for use in industrial scale fermentation processes for the enhanced expression/production of proteins of interest in the absence and/or in the presence of an inducing substrate.

The present disclosure provides mutant cells for the secretion of proteins and for the degradation of lignocellulosic biomass. Methods for the use of these cells are also provided. Specifically, the utility of combined genetic deletions of β-glucosidases and the catabolite repressor gene creA/cre-1 for protein secretion in fungal and yeast cells is disclosed.

The present disclosure provides mutant cells for the secretion of proteins and for the degradation of lignocellulosic biomass. Methods for the use of these cells are also provided. Specifically, the utility of combined genetic deletions of β-glucosidases and the catabolite repressor gene creA/cre-1 for protein secretion in fungal and yeast cells is disclosed.

Provided is a parent phytase variant, which relates to the technical field of protein engineering. The variant, relative to the parent phytase thereof, has one or more amino acid substitutions at positions corresponding to positions 295, 349, and 374 of SEQ ID NO: 1. Compared to the parent phytase, the variant has increased thermal stability.

The disclosure discloses an Aspergillus niger engineered strain for reducing byproduct succinic acid in a fermentation process of L-malic acid. The Aspergillus niger engineered strain is an Aspergillus niger engineered strain in which fumaric acid reductase frdA and fumaric acid reductase flavoprotein subunit frdB are simultaneously knocked out. The disclosure provides an frdA and frdB gene double-knockout Aspergillus niger strain, and a method for greatly reducing byproduct succinic acid in a fermentation process of L-malic acid. By the disclosure, the byproduct succinic acid accumulated in a production process of malic acid through fermentation of Aspergillus niger is significantly reduced, a cost in a downstream separation and purification process of malic acid is decreased, and good strains are provided for producing malic acid via industrial fermentation.

The disclosure discloses an Aspergillus niger engineered strain for reducing byproduct succinic acid in a fermentation process of L-malic acid. The Aspergillus niger engineered strain is an Aspergillus niger engineered strain in which fumaric acid reductase frdA and fumaric acid reductase flavoprotein subunit frdB are simultaneously knocked out. The disclosure provides an frdA and frdB gene double-knockout Aspergillus niger strain, and a method for greatly reducing byproduct succinic acid in a fermentation process of L-malic acid. By the disclosure, the byproduct succinic acid accumulated in a production process of malic acid through fermentation of Aspergillus niger is significantly reduced, a cost in a downstream separation and purification process of malic acid is decreased, and good strains are provided for producing malic acid via industrial fermentation.

The disclosure discloses an Aspergillus niger engineered strain for reducing byproduct fumaric acid in a fermentation process of L-malic acid. The Aspergillus niger engineered strain is an Aspergillus niger engineered strain in which a fumarate hydratase gene fum is knocked out. The disclosure overcomes the defects in the prior art, in the current process of producing malic acid through fermentation of Aspergillus niger, byproduct fumaric acid can be accumulated with the generation of malic acid so as to cause the improved cost of the subsequent malic acid purification process. The disclosure provides an Aspergillus niger engineered strain in which a fum gene is knocked out and a method for greatly reducing byproduct fumaric acid in the fermentation production of Aspergillus niger.

The disclosure discloses an Aspergillus niger engineered strain for reducing byproduct fumaric acid in a fermentation process of L-malic acid. The Aspergillus niger engineered strain is an Aspergillus niger engineered strain in which a fumarate hydratase gene fum is knocked out. The disclosure overcomes the defects in the prior art, in the current process of producing malic acid through fermentation of Aspergillus niger, byproduct fumaric acid can be accumulated with the generation of malic acid so as to cause the improved cost of the subsequent malic acid purification process. The disclosure provides an Aspergillus niger engineered strain in which a fum gene is knocked out and a method for greatly reducing byproduct fumaric acid in the fermentation production of Aspergillus niger.

Provided is a mutant β-glucosidase capable of more efficiently saccharifying biomass. A mutant β-glucosidase comprising an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 1, wherein the amino acid sequence has asparagine at one or more positions selected from the group consisting of positions corresponding to positions 787, 790, and 797 of SEQ ID NO: 1, and has β-glucosidase activity.